Biomedical device including encapsulation

ABSTRACT

A biomedical device including an energy source, an electro-active device operatively connected to the energy source, circuitry configured to control operation of the electro-active device, at least one barrier layer including at least one inorganic material surrounding the energy source, electro-active device and circuitry, and at least one molded layer surrounding the at least one barrier layer. A method for encapsulating electronic components of an electro-active biomedical device in a protective envelope containing a barrier layer including at least one inorganic compound, and a molded polymer overcoat.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/655,361, filed Jul. 20, 2017, entitled “BIOMEDICAL DEVICE INCLUDINGENCAPSULATION,” which claims the benefit of U.S. Provisional ApplicationNo. 62/365,248 filed Jul. 21, 2016, the contents of which isincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The invention relates to biomedical devices. In particular, theinvention relates to biomedical devices including an encapsulation toprotect the biomedical devices from contact with bodily fluids. Theencapsulation may also protect a user from exposure to components of thebiomedical device.

BACKGROUND OF THE INVENTION

Advances in medical devices have produced smaller and more complexmedical devices. Medical devices may incorporate powered functionalcomponents and a power source. The powered components may includecontrol elements incorporated in semiconductor chips, among otherthings. Examples of such devices may include implantable pacemakers,micro-energy harvesters, electronic pills for monitoring and/or testingbiological functions, surgical devices with active components,ophthalmic devices, contact lenses, infusion pumps, defibrillators,stents, and neurostimulators. Some of these devices are implantable,such as pacemakers, while others may contact tissue in some way forshort or long periods of time, such as a surgical instrument or contactlens, respectively.

Regardless of whether they are powered or not, medical devices need tobe biocompatible. However, introducing a power source and functionalcomponents into medical devices results in the need to protect them frombodily fluids as well as to protect a user or patient from coming intocontact with the power source or functional elements. For example, apacemaker and surgical instruments could contact blood and interstitialor other fluids; and a contact lens could contact tears or mucus.Contact with bodily fluids could short out a power source and renderfunctional components of medical devices inoperable. Conversely, contactof bodily fluids with, for example, anode or cathode material, could beharmful to a user or patient.

SUMMARY OF THE INVENTION

The present invention is directed to encapsulating electronic componentsof a biomedical device, such as a contact lens, in a protective envelopesuch that the biomedical device is able to withstand conditions to whichit is exposed during its manufacture and/or normal use.

An embodiment of the invention includes a biomedical device, such as acontact lens, including an energy source, an electro-active deviceoperatively connected to the energy source, integrated circuitryconfigured to control operation of the electro-active device, one ormore barrier layers comprising an inorganic material surrounding theenergy source, electro-active device and integrated circuitry, and oneor more molded layers surrounding the barrier layer(s). At least aportion of an external contour of the molded layer(s) may substantiallycorrespond to at least a portion of a desired external contour of thebiomedical device. The electro-active device of the biomedical devicemay comprise a liquid crystal variable optic. Also, the molded layer(s)of the biomedical device may comprise one or more cast molded polymers.

The biomedical device may also include one or more first conformalcoatings between the barrier layer(s) and the energy source,electro-active device and integrated circuitry, and/or one or moresecond conformal coating between the barrier layer(s) and the moldedlayer(s). The biomedical device may further include a coating layer onthe outer surface of the molded layer(s), and/or an embedmentsurrounding the molded layer(s).

Another embodiment of the invention includes a method for encapsulatingelectronic components of an electro-active biomedical device, such as acontact lens, in a protective envelope. The method includes applying oneor more barrier layers comprising at least one inorganic compound tosurround the electro-active biomedical device, and surrounding thebarrier layer(s) with one or more molded polymer layers. The electroniccomponents included in the method may comprise a liquid crystal variableoptic, and the molded polymer layer(s) may comprise a cast moldedpolymer.

The method may also include applying one or more first conformalcoatings between the barrier layer(s) and the electronic components,and/or applying one or more second conformal coatings between thebarrier layer(s) and the molded polymer layer(s). The method may furtherinclude applying a coating layer over the molded polymer layer(s),and/or forming an embedment surrounding the molded polymer layer(s).

Still other objects and advantages of the present invention will becomereadily apparent by those skilled in the art from the following detaileddescription, wherein is shown and described only the preferredembodiments of the invention, simply by way of illustration of the bestmode contemplated of carrying out the invention. As will be realized,the invention is capable of other and different embodiments, and itsseveral details are capable of modifications in various obviousrespects, without departing from the invention. Accordingly, thedrawings and description are to be regarded as illustrative in natureand not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned objects and advantages of the present invention willbe more clearly understood when considered in conjunction with theaccompanying drawings, in which:

FIG. 1 represents a cross-sectional view of an embodiment of theinvention comprising an electro-active insert for a contact lens;

FIG. 2 represents a close-up cross-sectional view of a portion of theembodiment shown in FIG. 1;

FIG. 3 represents a perspective view of an electro-active contact lens;and

FIG. 4 represents a flowchart illustrating an embodiment of a method forforming a biomedical device with a protective encapsulation.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

A biomedical device has a function. The construction of the devicesupports this function. To be able to carry out the function, thebiomedical device should be compatible with the human body. When thepowered components and power source are incorporated into a biomedicaldevice, issues arise with preventing damage to the powered componentsand power source from bodily fluids as well as harm to the human bodyfrom contact with the powered components and power source. Anyprotection for the biomedical device and/or the body must still permitthe biomedical device to function normally.

In the case of biomedical devices undergoing sustained contact with thehuman body, such as pace makers and contact lenses, it may be importantthat the powered components and power source are protected for anextended period of time. For example, a contact lens may need to protectthe powered components and power source for at least 3 years. A pacemaker may require protection for even longer.

An overmold or encapsulation structure may protect a biomedical deviceand the body with which the device is utilized and permit the biomedicaldevice to function. Embodiments of an overmold structure may include oneor more layers or other components. The layer(s) may have differentcompositions and functions and may or may not entirely surround thebiomedical device. A composition of a component of the overmold mayaffect the characteristics of that component. In some embodiments theovermold does not form the exterior surface of the biomedical device,but is rather embedded in the biomedical device.

Additionally, an overmold may need to be moldable to a specific shapefor a particular use of a biomedical device. Another factor affectingthe composition of components of the overmold is compatibility with eachother and with other parts of the biomedical device. Typically, theovermold or components thereof provide a chemical, electrical, and/ormoisture resistant barrier. As such, the overmold protects theelectronic components and power source of the biomedical device.

Similarly, the construction of the biomedical device should withstandconditions to which the device is exposed during use. While this mayinclude exposure to bodily fluids, it may also include exposure todisinfection and sterilization processes carried out prior to use. Also,biomedical devices such as contact lenses may be periodically subject tocleaning and sterilization, such as through chemical treatment and/orthe application of heat or radiation. The biomedical device should beable to withstand such treatment as necessary.

As an example, a contact lens including electro-active functionalcomponents and geometries is discussed herein. However, the structure ofthe overmold may be applied to any biomedical device. For example, theovermold/encapsulation could be applied to implantable pacemakers,micro-energy harvesters, electronic pills for monitoring and/or testingbiological functions, surgical devices with active components,ophthalmic devices, contact lenses, infusion pumps, defibrillators,stents, and neurostimulators. Any device that may be exposed to bodilyfluid for a period of time may beneficially include coatings andovermold/encapsulation as described herein.

Not all contact lenses or other biomedical devices need to include allcomponents of the overmold. Additionally, compositions of variouscomponents of the overmold may vary, depending on the structure,composition, use and/or environment of the device. For example, in thecontext of a contact lens, the overmold typically has optical propertiesthat do not interfere with the contact lens function.

First Conformal Coating

An electro-optic biomedical device, such as an electronically controlledvariable focus contact lens, may include a power source, electroniccontrol components and optic elements. All of these elements may besurrounded by one or more first conformal coatings. This first conformalcoating(s) (as discussed below, the structure may include otherconformal coatings) typically provide a smooth surface for theapplication of one or more barrier coatings. Along these lines, thefirst conformal coating(s) may eliminate sharp edges or corners of thepower source, electronic control components and optic elements tofacilitate the application of one or more barrier layers thereto. Spray,dip, or other conventional coating methods may be utilized to apply thefirst conformal coating(s). The first conformal coating(s) should beapplied in an amount sufficient to promote coverage of the electroniccomponents with one or more barrier layers as described below.Typically, the thickness of the first conformal coating(s) is in therange of from about 1 um to about 100 um. More typically, the thicknessof the first conformal coating(s) is in the range of from about 5 um toabout 10 um.

The first conformal coating(s) typically comprise one or morehydrophobic polymer(s). Suitable hydrophobic polymers generally includeacrylics, amides, imides, carbonates, dienes, esters, ethers,fluorocarbons, olefins, styrenes, vinyl acetals, vinyl and vinylidenechlorides, vinyl esters, vinyl ethers and ketones, vinylpyridine andvinypyrrolidone polymers. Combinations of such hydrophobic polymers mayalso be used.

The polymer(s) preferably have a water vapor transmission rate (WVTR) inthe range of from about 0.001 g/m²/day to about 100 g/m²/day. Typically,the WVTR is in the range of from about 1 g/m²/day to about 20 g/m²/day.Similarly, to maximize shelf life, the water uptake of the polymer(s)should be low. Typically, the water uptake of the polymer(s) is lessthan about 0.01% after 7 days at room temperature.

The polymer(s) utilized in the first conformal coating(s) may dependupon the function of the biomedical device. For example, if thebiomedical device is a contact lens, then the polymer(s) should havesuitable optical transmission properties. Such polymer(s) preferablyhave an optical transmission of about 80% or more of visible light.Typically, the optical transmission is about 85% or more. Moretypically, the optical transmission is about 90% or more. Along theselines, the polymer(s) preferably have a refractive index in the range offrom about 1.2 to about 1.8. Typically, the refractive index is in therange of from about 1.4 to about 1.6. Exemplary polymers having opticaltransmission and refractive indices within these ranges include Epotek301; Epotek 301-2; Nusil Med 10-6010; Epotek OG 603; Epotek OG 142-95;Epotek OG 142-112; Norland optical adhesives 61; Norland opticaladhesives 68; Norland optical adhesives 86; Momentive UV LSR 2060;Momentive LSR 7070; Momentive RTV 615; and paralyne.

Furthermore, the polymer(s) utilized in the first conformal coating(s)preferably have an Abbe number of about 30 or more. Typically, the Abbenumber is about 40 or more. Additionally, the polymer(s) advantageouslyhave a haze value of about 10% or less. Typically, the haze value isabout 2% or less. Also, the polymer(s) desirably have a b value based onL-A-B color space measurement of 10% or less. Typically, the b value is3% or less.

Prior to applying the first conformal coating(s), it may be necessary ordesirable to apply a pretreatment to the electronic components to helpensure that the first conformal coating(s) adheres thereto. Examples ofsuch pretreatments could include one or more processes to remove anysurface contamination or irregularities, or to create a desirablesurface texture. For example, grinding, turning, and/or other processescould be utilized. Additionally, one or more processes may be carriedout to degrease the substrate. For example, a dissolvent bath, steamcleaning, ultrasonic cleaning, plasma cleaning, and/or other processescould be utilized. Furthermore, blast cleaning may be utilized toincrease the surface roughness. Any one or more of these processes couldbe utilized. Alternatively, no process may be needed or desired toincrease adhesion of the first conformal coating(s).

Barrier Layer

The power source, electronic control components and optic elements, withor without the first conformal coating(s), may be at least partiallysurrounded by one or more barrier layers. The barrier layer(s) provide awater vapor barrier that reduces the rate of water vapor transmissionthrough the composite coatings forming the overmold. However, thebarrier layer(s) may have other additional or alternative functions. Thebarrier layer(s) should be free of defects such as pin-holes and otherknown defects that may commonly occur during thin film depositionprocesses.

The thickness of the barrier layer(s) may vary. For example, thethickness may commonly be in the range of from about 1 nm to about 1 mm.Typically, the thickness is in the range of from about 10 nm to about500 nm. More typically, the thickness is in the range of from about 30nm to about 200 nm. Particular embodiments include barrier layerthicknesses of 50 nm, 100 nm and 200 nm.

To protect the functionality of the power source, electronic componentsand optic elements, the barrier layer(s) should have a water vaportransmission rate (WVTR) in the range of from about 1 to about 10⁻⁶g/m²/day. Typically, the WVTR is in the range of from about 10⁻² toabout 10⁻⁶ g/m²/day. More typically, the WVTR is in the range of fromabout 10⁻⁴ to about 10⁻⁶ g/m²/day.

A variety of materials may be utilized in the barrier layer(s). Usefulmaterials should be compatible with the underlying power source,electronic control components and optic elements, any conformal coatingsapplied thereto, as well as the one or more molded polymer layer(s).Typically, the materials of the barrier layer(s) also have a strongadhesion to the first conformal coating(s) or, in the absence of thefirst conformal coating(s), to the underlying power source, electroniccontrol components and optic elements that may be utilized to form theelectro-active optic portion of the lens.

Typically, the barrier layer(s) comprise one or more inorganicmaterials. The inorganic material(s) provide water vapor protection forthe power source, electronic control components and optic elements byreducing the WVTR. Suitable inorganic material(s) for the barrierlayer(s) may include one or more of Al₂O₃; TiO₂; Ta₂O₅; Nb₂O₅; HfO₂;ZrO₂; SiO₂; ZnO; MgO; Ga₂O₃; La₂O₃; Y₂O₃; Yb₂O₃; Sc₂O₃; Er₂O₃; V₂O₅;CeO₂; CaO; or CuO. Typically, inorganic material(s) of the barrierlayer(s) include one or more of Al₂O₃, SiO₂, and/or TiO₂. For opticalapplications, inorganic material(s) that are sufficiently transparentshould generally be utilized, such as one or more of Al₂O₃, SiO₂, andTiO₂.

If the biomedical device is a contact lens, then the material(s)selected for the barrier layer(s) is preferably optically clear. Alongthese lines, the barrier layer(s) advantageously have a refractive indexin the range of from about 1.1 to about 2.95. Typically, the refractiveindex is in the range of from about 1.4 to about 1.7. More typically,the refractive index is in the range of from about 1.4 to about 1.6.Furthermore, the barrier layer(s) desirably have an optical transmissionin the range of from about 60% to about 100%. Typically, the opticaltransmission is in the range of from about 80% to about 100%. Moretypically, the optical transmission is in the range of from about 85 toabout 99%. Suitable inorganic materials that meet these requirementsinclude one or more of Al₂O₃, SiO₂, and TiO₂.

Various methods may be utilized to deposit the barrier layer(s). Forexample, chemical vapor deposition (CVD), physical vapor deposition(PVD) or atomic layer deposition (ALD) may be utilized to deposit thebarrier layer(s). Other methods could include spray coating, dipcoating, spin coating, or other types of coating. Typically, the barrierlayer(s) is deposited or formed at a temperature of about 20° C. toabout 500° C. More typically, the barrier layer(s) are formed at atemperature of about 20° C. to about 60° C.

The process may be carried out at sub-atmospheric pressures. Forexample, the process could be carried out at a pressure in the range offrom about 500 millitorr to about 760 torr. Typically, the process offorming the barrier layer(s) is carried out at a pressure in the rangeof from about 10⁻² mbar to about 10⁻⁸ mbar.

Prior to applying the barrier layer(s) to the electronic componentsand/or first conformal coating(s), it may be necessary or desirable toapply a pretreatment to the electronic components and/or first conformalcoating(s) to help ensure that the barrier layer(s) adhere. Examples ofsuch pretreatments could include one or more processes to remove anysurface contamination or irregularities, and/or to create a desirablesurface texture. For example, grinding, turning, and/or other processescould be utilized.

Additionally, one or more processes may be carried out to degrease thesubstrate. For example, prior to applying the barrier layer(s) to theelectronic components, a dissolvent bath, steam cleaning, ultrasoniccleaning, plasma cleaning, and/or other processes could be utilized.Conversely, prior to applying the barrier layer(s) to the firstconformal coating(s), an oxidizing cleaning, an oxygen plasma cleaning,a UV-ozone cleaning, and/or in-situ O₂-plasma cleaning could beutilized. Furthermore, blast cleaning may be utilized to increase thesurface roughness. Any one or more of these processes could be utilized.Alternatively, no process may be needed or desired to increase barrieradhesion.

Second Conformal Coating

After applying the barrier layer(s), one or more second conformalcoatings may be applied to at least partially surround the barrierlayer(s). The second conformal coating(s) may protect the barrierlayer(s) during handling of the structure. The second conformalcoating(s) may also reduce variations in the surface of the structureafter application of the barrier layer(s).

The second conformal coating(s) generally should have a thicknesssufficient to reduce surface variations in the barrier-coated structureto a desired degree, and/or to provide a desired degree of protection.Typically, the second conformal coating(s) have a thickness in the rangeof from about 500 nm to about 1 mm. More typically, the second conformalcoating(s) have a thickness in the range of from about 1 μm to about 20μm. Most typically, the second conformal coating(s) have a thickness inthe range of from about 1 μm to about 10 μm.

The materials utilized in the second conformal coating(s) may be thesame, or substantially the same, as the materials mentioned above forthe first conformal coating(s). For instance, if the biomedical deviceis contact lens, the polymers utilized in the second conformalcoating(s) desirably have the same characteristics as the materials usedin the first conformal coating(s) mentioned above. Along these lines,the properties of the polymers utilized in the second conformalcoating(s) (i.e., the optical transmission, refractive index, Abbevalue) may be the same or substantially the same as those propertiesmentioned above for the polymers utilized in the first conformalcoating(s). Preferably the same materials are used in both the first andsecond conformal coating(s) to reduce any internal stresses due tothermal expansion and contraction.

Molded Layer

After applying the barrier layer(s) and any first and second conformalcoating(s), one or more molded layers may be formed around at least aportion of the entire structure. Typically, the molded layer(s) surroundthe entire structure and have an exterior contour that is compatiblewith the desired shape of the biomedical device. For example, if thebiomedical device is a contact lens, the molded layer(s) may have ashape similar to the shape of the contact lens. Other biomedical devicesmay have other shapes. It may also be possible for the molded layer(s)to have an outer shape that has no relationship to a functional aspectof the biomedical device, unlike a contact lens.

The materials utilized in the molded layer(s) should be the same orsubstantially the same to those of the first and/or second conformalcoating(s). By using the same or substantially the same materials, themolded layer(s) will have a thermal expansion coefficient that is thesame or very close to that of the first and/or second conformalcoating(s), which may help retain interlayer adhesion. However, to theextent that the molded layer(s) and first and second conformalcoating(s) comprise different materials, such materials shouldnonetheless have sufficiently similar thermal expansion coefficients toprevent delamination at temperatures to which the device is exposedduring manufacture, storage and use.

The materials used in the molded layer(s) typically include one or morepolymers. Any of the polymer(s) described above with respect to thefirst and/or second conformal coating(s) may also utilized in the moldedlayer(s). For instance, like the polymer(s) of the first and/or secondconformal coating(s), the polymer(s) of the molded layer(s) may behydrophobic. In addition, the polymer(s) included in the first and/orsecond conformal coating(s), barrier layer(s), and molded layer(s) maybe selected based upon compatibility with each other, thermal expansionproperties and/or surface adhesion characteristics, among other factors.

With any biomedical device, the polymer(s) of the molded layer(s) shouldbe biocompatible. Moreover, the polymer(s) of the molded layer(s) shouldalso be compatible with substances with which the polymer(s) may contactduring use of the device. For instance, in the context of a contactlens, typically, the polymer(s) should be compatible with lens cleaningsolution, mild acid disinfectant, and common organic solvents.

The polymer(s) of the molded layer(s) preferably have a low water vaportransmission rate (WVTR). Along these lines, the WVTR of the polymer(s)is typically in the range of from about 0.001 g/m²/day to about 100g/m²/day. More typically, the WVTR is in the range of from about 1g/m²/day to about 10 g/m²/day. Similarly, to maximize shelf life, thewater uptake of the polymer(s) should be low. Typically, the wateruptake of the polymer(s) is less than about 0.01% after 7 days at roomtemperature.

Also, like the polymer(s) utilized in the first and/or second conformalcoating(s), the polymer(s) utilized in the molded layer(s) may dependupon the function of the biomedical device. Along these lines, when thebiomedical device is a contact lens, the polymer(s) of the moldedlayer(s) may desirably have the same, or substantially the same, opticaltransmission and refractive index as those utilized in the first and/orsecond conformal coating(s). Similarly, the Abbe number, b value andhaze value of the polymer(s) of the molded layer(s) may also be thesame, or substantially similar, to those of the polymer(s) of the firstand/or second conformal coating(s).

In some cases, one or more additive(s) may be added to the polymer(s) orpolymer mixtures for various reasons. For example, the additive(s) mayimprove mechanical strength and/or water uptake properties of thepolymer(s). As such, if hydrophobic polymer(s) are used in the moldedlayer(s), the additives may improve its hydrophobic nature.

Physical attributes of the polymer(s) may vary depending upon theapplication. For example, if the biomedical device is a contact lens,the polymer(s) may be softer. Alternatively, if the biomedical device isa pacemaker, the polymer(s) may be harder. Typically, the moldedlayer(s) of a contact lens have a Shore D hardness greater than about40D. More typically, the molded layer(s) of a contact lens have a ShoreD hardness greater than about 65D.

The physical characteristics of the polymer(s) may also depend upon thecomposition of the barrier layer(s), first and second conformalcoating(s), and/or any other layers applied over the molded layer(s).For example, when the biomedical device is a contact lens, it isdesirable for the polymer(s) of the molded layer(s) to have a strongadhesion to hydrogel, which forms the outermost layer of the contactlens. Along these lines, when the biomedical device is a contact lens,it is also desirable for the polymer(s) of the molded layer(s) to becompatible with TOPAS, polypropylene, polyimide, polyethylene, and/orother materials utilized to make contact lenses.

The polymer(s) making up the molded layer(s) may have any suitable form.However, they typically are liquid prior to curing. If the polymer(s)are liquid, they typically have a viscosity in the range of from about10 to about 500000 CP. More typically, the viscosity is in the range offrom about 10 CP to about 100000 CP. Most typically, the viscosity is inthe range of from about 10 CP to about 1000 CP. The viscosity may beadjusted by adding suitable solvents.

A liquid polymer may permit the molded layer to be cast in a mold. Forexample, polymer may be introduced into a lower mold portion, thebarrier coated electronics arranged on the polymer. Then, additionalpolymer may be added to the lower mold to cover the barrier coatedelectronics. An upper mold portion may then cover the polymer to shapethe upper surface of the polymer. The mold may have a desired shape,such as a contact lens shape, depending upon the biomedical device beingfabricated.

After the polymer(s) and electronics are arranged in the mold, thepolymer(s) may be cured utilizing a variety of different techniques.such as heat and/or electromagnetic radiation. If heat is utilized tocure the polymer(s), the temperature carried out should be such that itdoes not damage the underlying elements and/or the underlying layers.Along these lines, the curing is typically carried out at a temperaturebelow about 80° C. More typically, the curing is carried out at atemperature below about 50° C. Most typically, the curing is carried outat a minimum of about 20° C.

Alternatively, if electromagnetic radiation is utilized, it may havewavelengths from ultraviolet to visible light. In other words, theradiation may have a wavelength in the range of from about 10 nm toabout 710 nm. Typically, ultraviolet radiation having a wavelength inthe range of from about 420 nm to about 460 nm is useful. According tospecific embodiments, wavelengths of 420 nm, 435 nm, or 460 nm areutilized.

Combinations of radiation and heat may also be utilized. Along theselines, according to one embodiment, the UV radiation applied should beunder conditions of about 60° C. Other techniques that may be utilizedinclude thermal curing, three-dimensional printing, or other similarmolding or curing methods. The entire structure could be cured at onceor spot curing could be utilized.

The curing time may depend upon the polymer(s) utilized, the method ofcure and the temperature. The cure time may depend upon the desireddegree of polymerization. As with the temperature, the curing timeshould be less than a period that would damage powered functionalcomponents. At a temperature of about 60° C. and below, the curing timemay be about 24 hours to about 96 hours. If the temperature is about 90°C. or below, the curing time may be less than about 30 minutes. If thetemperature is about 100° C. or above, the curing may be carried out forabout 5 minutes or less. Each layer of the structure may be at leastpartially cured prior to applying any additional layers. Conversely,each layer may be fully cured prior to applying any additional layers.Typically, the molding and curing processes may be carried out atatmospheric pressure.

After curing the polymer(s), the polymer coated structure may be furtherprocessed. Such further processing can include direct incorporation intoa biomedical device, or the application of additional coating layers orsurface modification techniques as desired. For example, if thebiomedical device is a contact lens, one or more adhesion promotionlayers may be applied around at least a portion of the molded layer(s)to enhance the adhesion of hydrogel thereto. The adhesion promotionlayer(s) may comprise a liquid primer. The adhesion promotion layer(s)may be applied by spray coating, spin coating, dip coating, and othersimilar types of coating processes.

Similarly, if the biomedical device is a contact lens, the moldedlayer(s) may be treated with plasma, UV, or corona to create surfacegroups and utilize them to enhance adhesion of hydrogel thereto. Anexemplary process includes an O₂ plasma treatment followed by a Silanechemistry treatment and encapsulation of a hydrogel.

Additionally, when the biomedical device is a contact lens, theshrinkage of the polymer(s) during the molding process should be asminimal as possible. Typically, the shrinkage of the polymer(s) is about20% or less. More typically, the shrinkage of the polymer(s) is about 5%or less. Most typically, the shrinkage of the polymer(s) is about 2% orless. Additionally, electrical resistivity of the polymer(s) typicallyis as large as possible. Along these lines, the resistivity is typicallymultiple megaohms, such as at least about 10¹² Ω-cm.

According to some embodiments, the structure, including the moldedpolymer layer(s), may be the final form of the biomedical device. Otherembodiments may include additional structure surrounding the moldedlayer(s). For example, if the biomedical device is a contact lens, thenthe molded layer(s) may be surrounded by a typical hydrogel embedment.Methods for forming the hydrogel embedment are known and need not bedescribed in detail.

FIGS. 1 and 2 are cross-sectional views of an embodiment ofencapsulation layers for a powered contact lens insert. Along theselines, FIG. 1 is a cross-sectional view of the powered components andpower source of the insert enveloped in an embodiment of theencapsulation. FIG. 2 is a close-up cross sectional view of a portion ofthe embodiment shown in FIG. 1 illustrating the multi-layer compositestructure of the overmold encapsulation. The powered contact lens mayinclude an optical component 200, integrated circuitry 204, and a powersource 205, such as a micro-battery. The optical component 200 maycomprise a front optic 201, a middle optic 202, a back optic 203.According to some embodiments, the front optic 201, middle optic 202,and back optic 203 may include cyclic olefin copolymer. Alternatively,the optical component 200 may comprise a liquid meniscus lens comprisingtwo immiscible fluids. Additionally, the integrated circuitry 204 mayinclude a silicon-based chip. Furthermore, an outer-most layer of thepower source 205 may include metal interconnects, such as brass ortitanium, or a polymer film capable of sealing. Along these lines, theintegrated circuitry 204 and power source 205 may be located outside ofan optical zone of the contact lens that the wearer looks through. Theembodiment shown in FIGS. 1 and 2 includes a first conformal coating206, a barrier layer 207, a second conformal coating 208, a moldedpolymer layer 209, and a surface coating 210. These various layers maybe referred to collectively as an encapsulation layer 211.

FIG. 3 represents a perspective view of an entire contact lens thatincludes an electro-active lens insert comprising hydrogel layer 300surrounding an insert containing power source 301 and a plurality ofother components, such as integrated circuitry 303 and optical component302. The power source 301 may be in the shape of an annulus or a portionof an annulus.

FIG. 4 provides a flowchart illustrating elements of an embodiment of anovermolding process as described above, and as used, for example, inprocesses where the biomedical device to be formed is a powered contactlens. The process may begin with an optional step 401 to coat one ormore components before they are assembled into a work piece. Accordingto some embodiments, the components may include: a power supply, supportsubstrates on which to mount various components, interconnect featuresto provide electrical interconnection between the various components,electrical circuit components, such as integrated circuits and passiveelectrical devices, and electro-active elements, such as electro-activeoptical focal power modifying components. Each component may be formedwith a different type of surface layer and may require a coating toalign the respective surface characteristics with the rest of theovermold processing. The various components may be assembled 402 into awork piece.

Thereafter, the process may continue to step 403 to apply one or morefirst conformal coatings to at least a portion of the work piece. One ormore barrier coatings may then be deposited, at step 404, to at least aportion of the work piece. Subsequently, at step 405, one or more secondconformal coatings may be applied to at least a portion of the workpiece. The second conformal coating(s) may comprise materials that arethe same or substantially the same as those of the first conformalcoating(s). At step 406, one or more molded layers may be formed aroundat least a portion of the work piece. The molded layer(s) may partiallyor entirely surround the work piece and be formed to an exterior contourcompatible with the desired shape of the resulting biomedical device.The resulting molded piece may be further processed to make a biomedicaldevice of various kinds, such as a contact lens. Optionally, at step407, the resulting molded piece may be subject to treatments to modifyits surface, such as plasma treatments, so that it is compatible withfurther processing. Alternatively, an additional layer may be applied tothe resulting molded piece to provide desired surface characteristics.

The foregoing description of the invention illustrates and describes thepresent invention. The disclosure shows and describes only the preferredembodiments of the invention, but as aforementioned, it is to beunderstood that the invention is capable of use in various othercombinations, modifications, and environments and is capable of changesor modifications within the scope of the inventive concept as expressedherein, commensurate with the above teachings, and/or the skill orknowledge of the relevant art. Accordingly, the description is notintended to limit the invention to the form of the best modes ofpracticing the invention disclosed herein, and it is intended that theappended claims be construed to include alternative embodiments.

1. A method for encapsulating electronic components of an electro-activebiomedical device in a protective envelope, the method comprising:applying a barrier layer comprising at least one inorganic compoundsurrounding the electro-active biomedical device; and surrounding thebarrier layer with a molded polymer layer.
 2. The method according toclaim 1, wherein the at least one inorganic compound comprises at leastone of Al₂O₃, TiO₂, Ta₂O₅, Nb₂O₅, HfO₂, ZrO₂, SiO₂, ZnO, MgO, Ga₂O₃,La₂O₃, Y₂O₃, Yb₂O₃, Sc₂O₃, Er₂O₃, V₂O₅, CeO₂, CaO, or CuO.
 3. The methodaccording to claim 1, further comprising: applying a conformal coatingbetween the barrier layer and the electronic components.
 4. The methodaccording to claim 1, further comprising: applying a conformal coatingbetween the barrier layer and the molded polymer layer.
 5. The methodaccording to claim 1, further comprising: applying a coating layer overmolded polymer layer.
 6. The method according to claim 1, furthercomprising: forming an embedment surrounding the molded polymer layer.7. The method according to claim 1, wherein the electro-activebiomedical device is a contact lens and the electronic componentscomprise a liquid crystal variable optic.
 8. The method according toclaim 1, wherein the molded polymer layer is hydrophilic.
 9. The methodaccording to claim 1, wherein the molded polymer layer comprises atleast one of acrylics, amides, imides, carbonates, dienes, esters,ethers, fluorocarbons, olefins, styrenes, vinyl acetals, vinyl andvinylidene chlorides, vinyl esters, vinyl ethers and ketones,vinylpyridine, and vinypyrrolidone polymers.
 10. The method according toclaim 9, wherein the molded polymer layer comprises at least one ofEpotek 301, Epotek 301-2, Nusil Med 10-6010, Epotek OG 603, Epotek OG12-95, Epotek OG 12-112, Norland optical adhesives 61, Norland opticaladhesives 68, Norland optical adhesives 86, Momentive UV LSR 2060,Momentive LSR 7070, Momentive RTV 615, paralyne and combinationsthereof.